The rangers had come across wood scattered on the ground from much larger trees than the few dwarfs currently in the area, including logs that were several feet long.

"Walking through the area, they're everywhere," said Joel Barker, an environmental scientist at Ohio State University who's leading a study of the mummified forest. "You'd have trouble not tripping over them."

The park rangers "had no idea what they were," but Barker suspected they must be millions of years old.

When Barker and colleagues found where the scattered logs were coming from—a slope that had been eroded by a river—they dug in and found many more logs, as well as leaves and seedpods.

"When we started pulling leaves out of the soil, that was surreal, to know that it's millions of years old and that you can hold it in your hand," Barker said at an annual meeting of the American Geophysical Union in San Francisco earlier this week.

Ecosystem on the Edge?

The mummified trees were likely preserved so long because they were buried quickly by landslides and thus protected from air and water, which hastens decomposition.